Molecular properties of Kcv, a virus encoded K+ channel

Autor(en): Pagliuca, Cinzia
Goetze, Tom Alexander
Wagner, Richard 
Thiel, Gerhard
Moroni, Anna
Parcej, David
Stichwörter: Biochemistry & Molecular Biology; KCSA; MEMBRANES; PERMEATION; PICHIA-PASTORIS; POTASSIUM-CHANNEL; PROTEIN; SELECTIVITY FILTER; STOICHIOMETRY; STREPTOMYCES-LIVIDANS; VESICLES
Erscheinungsdatum: 2007
Herausgeber: AMER CHEMICAL SOC
Journal: BIOCHEMISTRY
Volumen: 46
Ausgabe: 4
Startseite: 1079
Seitenende: 1090
Zusammenfassung: 
The miniature viral K+ channel Kcv represents the pore module of all K+ channels. A synthetic gene of Kcv with an elevated GC content compared to that of the wild-type gene was expressed heterologously in Pichia pastoris, and the purified protein was functionally reconstituted into liposomes. Biochemical assays reveal a remarkable cation selctive stability of the channel tetramer via SDS-PAGE. Only cations, which permeate Kcv, were able to protect the oligomer against disassembly into monomers at high temperatures. Electrophysiological characterization of the single Kcv channel reveals a saturating conductance (Lambda(max)) of 360 pS; the single-channel current-voltage relation was strongly rectifying with a negative slope conductance at extreme voltages. The channel was highly selective for K+ and was blocked by Ba2+ and in a side specific manner by Na+ and Cs+ also. The channel conducted Rb+, but as a consequence, the channel was shifted into a hyperactive state. We conclude that specific binding interactions of cations in the conductive pathway are an important determinant of channel stability and function.
ISSN: 00062960
DOI: 10.1021/bi061530w

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